From 108a3865f43330b581d35b9cf6ecb1e0a1da5d49 Mon Sep 17 00:00:00 2001 From: Ryan Cohen Date: Sat, 26 Nov 2022 17:22:51 -0500 Subject: [PATCH] term/i386/pc/vga_text: Prevent out-of-bounds writes to VGA text buffer Coordinates passed to screen_write_char() did not have any checks to ensure they are not out-of-bounds. This adds an if statement to prevent out-of-bounds writes to the VGA text buffer. Reference:https://git.savannah.gnu.org/cgit/grub.git/commit?id=108a3865f43330b581d35b9cf6ecb1e0a1da5d49 Conflict:NA Signed-off-by: Ryan Cohen Reviewed-by: Daniel Kiper --- grub-core/term/i386/pc/vga_text.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/grub-core/term/i386/pc/vga_text.c b/grub-core/term/i386/pc/vga_text.c index 669d06fad..b88fa9d2e 100644 --- a/grub-core/term/i386/pc/vga_text.c +++ b/grub-core/term/i386/pc/vga_text.c @@ -63,7 +63,8 @@ static grub_uint8_t cur_color = 0x7; static void screen_write_char (int x, int y, short c) { - VGA_TEXT_SCREEN[y * COLS + x] = grub_cpu_to_le16 (c); + if (x < COLS && y < ROWS && x >= 0 && y >= 0) + VGA_TEXT_SCREEN[y * COLS + x] = grub_cpu_to_le16 (c); } static short -- 2.28.0.windows.1